This invention relates to pulleys generally. It relates more particularly to an improved marine block.
Marine blocks or pulleys are used to facilitate drawing lines to move sails, booms and other parts, particularly on a sailboat. Such a block invariably includes a pair of spaced-apart cheek plates for supporting the opposite ends of an axle. A sheave is rotatively mounted on the axle between the plates. The plates are shackled to a fixed support and the line is trained around the sheave. If the block is to operate properly, it is essential that the sheave rotate freely on its axle. This is especially so in the case of marine blocks which are used to facilitate raising and lowering sails and the like, which efforts must be accomplished readily in a minimum amount of time, especially when racing. Accordingly, usually a ball bearing unit is incorporated between the sheave and axle to enable the sheave to rotate freely.
After a time, however, pulleys generally and marine blocks in particular do not operate as well as they might because the sheave does not always rotate freely on its axle. This is because dirt, salt and other debris tends to accumulate between the sheave and the block cheek plates and more importantly at the rotary joint between the sheave and the block axle. Even if that joint includes a bearing unit, the bearings and their races become fouled so as to inhibit free rotation of the sheave.
In the case of some blocks, it is possible to alleviate this problem by disassembling the block and cleaning its various parts. However, in order to clean the block in that fashion, it must be disconnected and taken out of service before that maintenance step can be performed. That, of course, requires considerable time and effort on the part of the boat owner. Many blocks, however, cannot be disassembled; their cheek plates are permanently riveted together. Therefore, in the case of those blocks, that option is not even available to the boat owner.